Norbert Hartl wrote on 11. 6. 2018 23:38:
Am 11.06.2018 um 16:48 schrieb Richard O'Keefe <rao...@gmail.com
<mailto:rao...@gmail.com>>:
I'm really baffled here.
Look at the definition at json.org <http://json.org>.
An object is an UNORDERED set of name/value pairs.
Or look at ECMA-404, which json.org <http://json.org> points to.
The JSON syntax does not impose any restrictions on
the strings used as names ... and DOES NOT ASSIGN
ANY SIGNIFICANCE TO THE ORDERING.
When you say that "it is pretty clear that the order is
important for that format" I fail to understand you.
It is absolutely clear that by design the order is NOT
important or even significant for JSON.
JSON Pointer does not provide any way to refer to order
in an "object": /2 applied to an object will look for
the name "2" as a string.
JSONPath does not provide any way to refer to order in
an "object": [2] applied to an object will look for
the name "2" as a string.
JSON Schema does not provide any way to constrain or
refer to order in an "object".
As for databases, Postgres documentation says of JSONB
that "Insignificant whitespace is discarded, and
the order of object keys is not preserved."
If you are communicating with someone else who is using
pseudo-JSON that does attach semantics to the order of
the name/value pairs, then of course you do whatever you
have to in order to communicate successfully. Just don't
think of it as JSON. If you have two programs whose
protocol you control, again you can use JSON syntax with
different semantics all you want. Just don't think of it
as JSON. Heck, if it is important to you to distinguish
between integer 1 and floating point 1.0, you can add
your own semantics if you like, but *JSON* doesn't
distinguish them.
As for MongoDB, it works with BSON (which is richer than
JSON. which is why "MongoDB Extended JSON exists), and
does some seriously odd things, like regarding
{} and {"a": null} as equal. (According to the 3.6 manual.)
Do whatever you have to do to get the job done,
but just remember that most JSON tools think they are
dealing with *JSON*, not something else that looks
like it but has different semantics, and can be relied
on to preserve or respect *JSON* semantics, not some
other semantics unknown to them.
It was not talked about JSON but about a content format that uses JSON
as its encoding. So if that format how poor it appears to use puts
significance to the ordering why you even start to argue?
Why care about JSON tools and talk about semantics because there is no
semantic in an encoding format. It is an encoding format of nested keys
and values and arrays. No key or value has special meaning. It is dumb
JSON.
You can use every JSON tool to read and destroy it. Like you can read a
binary file in a text editor apply newline conventions and destroy it.
What is the point here?
I presume the point here is that, if you presume JSON is mostly used
with JavaScript, then JSON _is_, in effect, keeping the order. If I am
not mistaken, it is already part of the spec a few years already that
enumeration on the object keys MUST respect the order in which keys were
created, and JSON algorithm prescribes that keys are created in the
order they are read when parsing, and should use the internal order of
keys when stringifying. So, JSON is de facto preserving order, though de
iure it is not. But the fact that is does it de facto, leads to creation
of order-dependent services. Not saying this is correct per specs, not
that it is correct from general design PoV, just that it happens because
order preserving _is_ already there, so the code may end up using it,
even unconsciously.
This "JSON is in practice order-preserving" implementation artifact then
leaks out when some protocols end up requiring it.
Then other languages may feel the need to have this "industry standard"
of order-preserving JSON to have as well.
OP correct me if I am wrong.
Herby
Norbert
